Photo by Bet Zimmerman Smith
I found this
Brown-headed Cowbird egg in an Eastern Bluebird nest. (See full resolution version.) The nest was in a Gilwood box. I rarely see cowbird eggs in my boxes. I make sure the entrance holes are not enlarged, which may deter them somewhat.
Cowbirds are parasitic nesters. They find an active nest, and before incubation begins they remove one of the host's eggs and replace it with their own, leaving the host bird to raise their young (unless the eggs are detected and removed by the host.) Read more about these
Also see photo of a
Cowbird egg in a sparrow nest.
References and More Information:
Pictures of bluebirds and other cavity nesters
Previous Pictures of the Week: © Original photographs are copyrighted, and may not be used without the permission of the photographer. Please honor their copyright protection. If you would like to use a photo for educational purposes, you can
Tips for photographing cavity nesters
June 11, 2006 - Great Crested Flycatcher
June 19, 2006 - Snake Lick
June 26, 2006 - House Finch Nest
July 3, 2006 - Tree Swallow in Flight
July 17, 2006 - Bluebird Battle
July 24, 2006 - Bear Attack
August 1, 2006 - Neglected Nestboxes (House Sparrow nests)
August 14, 2006 - Threesome (Bluebird Babes)
August 28, 2006 - Peering (flicker)
January 2007 - New Hill Trail (Sialis)
February 12 2007 - Sharp-shinned? Hawk feeding on dead starling
February 19, 2007 - Joe's Cafe (Suet/Mealworm Feeder)
March 25, 2007 - Sunflower Eater
February 2007 - Snags & Suet (Pileated Woodpeckers)
May 2007 - Birdcam Shots and Birdcam Photo Album
May 12, 2007 - Carolina Wren nest in a boot May 25, 2007 -
Batman Bird (Tree Swallows) June 2007 -
Bluebird nest of cattails, one with leaves, and a TRES nest with maple seeds
June 20, 2007 - Nine Egger (Tree Swallow nest)
June 27, 2007 - Black-capped Chickadees (funny and serious photos)
July 7, 2007 - Anting and Sunbathing
Red-shouldered Hawk perching on nestbox
November 18, 2007 - Western Bluebirds at the Spa March 15, 2008 -
Under Construction - Eastern Bluebirds Building a Nest
April 9, 2008 - Bluebird Battle in PA
April 10, 2008 - Mouse Surprise
April 15, 2008 - Bluebird News (nest in paper box)
April 23, 2008 - My personal nightmare
April 25, 2008 - Brave White-breasted Nuthatch
April, 2008 - How an egg hatches
May 3, 2008 - Newborn Blue (baby hatching)
May 3, 2008 - Brave Blue (female on nest)
May 14, 2008 - House Wren Havoc (eggs pecked)
May 25, 2008 - House Wren Takeover (of nest, more pecked eggs)
May 29, 2008 - Take Your Pick (parents feeding fledgling)
June 10, 2008 - That Look Belongs in a Holster (female MOBL)
August 23, 2008 - Cat on Nestbox
September 28, 2008 - HOSP on the House
October 10, 2008 - Cuddling nestlings (taken in summer time)
October 27, 2008 - HOSP in flight
October, 2008 - Possible double and dwarf egg in one nest
December 16, 2008 - The Next Generation (children building boxes)
January 22, 2009 - Blue with Cold January 28, 2009 -
Prothonotary Warbler on a camper | Nest building PROW | PROW nesting in tree cavity
May, 2009 - To Kill a Mockingbird (Snake eating mockingbird - may be disturbing)
May 21, 2009 - Should I Stay or Should I Go Now? (Titmouse nestling in box)
May 25, 2009 - Which of these is not like the others? (Cowbird egg)
May 23, 2009 - The Honeypot at the end of the rainbow (bumblebee nest)
June 20, 2009 - House Wren nest decorated with Western Bluebird feathers
June 20, 2009 - Wonderful WEBLS of WA
June 20, 2009 - Bluebirds of Bickleton
July 12, 2009 - Hairy Shrimp (newborn bluebirds)
July 2009 - Diet (bluebird with earthworm in beak)
July 2009 - Bluebirds nesting outside of cavity
July 19, 2009 - HOSP on Holiday
July 20, 2009 - Pink bluebird eggs
August 2, 2009 - Pinkies (baby mice)
August 2, 2009 - En garde (male bluebird in box)
September 29, 2009 - 1917 instructions for bird house construction
I forget when - Rainbox
April 11, 2010 - nuthatch bark
April 12, 2010 - My first white egg
April 12, 2009 - TUTI nest by Keith Kridler
May 2010 - TUTI newborns
May 2010 - Christmas Chickadee
May 2010 - Bluebird and Chickadee eggs in the same nest
June 2012 - Paparazzi
April 2013 - Under Construction - Titmouse nestbuilding
July 2013 - Pink Bluebird Eggs
July 2014 - Cowbird egg in Eastern Bluebird nest
July 2014 - Newborn HOSP
July 2015: Patience Pays (Male Eastern Bluebird)
You cannot begin to preserve any species of animal unless you preserve the habitat in which it dwells. Disturb or destroy that habitat and you will exterminate the species as surely as if you had shot it. So conservation means that you have to preserve forest and grassland, river and lake, even the sea itself. This is vital not only for the preservation of animal life generally, but for the future existence of man himself—a point that seems to escape many people.
-Gerald Durrell, The Nature Conservancy
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